1. Field of the Invention
This invention relates to packaging and more particularly to a heat shrink package having perforations for providing a frangible access panel defined by perforations in the heat shrink package.
2. Description of the Prior Art
The art of heat shrink wrapping has provided many novel and inexpensive packages over the last decade. Typically, a single article or an array of articles are located on a conveyor and are loosely wrapped with a plastic material such as polyethylene which will shrink upon the application of heat. The article or articles wrapped with the heat shrinkable material are passed through a heat shrink oven to cause shrinking of the plastic material to thereby conform to the outer dimensions of the article or articles. The heat shrink package provides a protective covering for the article or articles, as well as a mechanical package for holding the plurality of articles in an array.
Some in the prior art have found it necessary to remove a portion of the shrink wrap package for applying price markings or tax stamps to the article or array of articles enclosed within the shrink wrap package. For example, cigarette packs or other packages requiring tax stamps are preferably packaged in a carton array with a removable panel disposed on one edge. The panel may be removed and the tax stamp applied to each of the array of articles while the articles are still maintained in the shrink wrap package. Similarly, articles to be sold in retail outlets may be conveniently price marked through the use of a removable panel prior to the removal of the individual articles from the heat shrink package.
U.S. Pat. No. 3,016,131 to Kennedy discloses a heat shrink package of polymetric film which is provided with a desired slit pattern which opens when stretched in the heat shrinking process.
U.S. Pat. No. 3,047,140 to Robins teaches a shrink wrap package of a plurality of articles with perforations to permit ready detachment of a single article from the package.
U.S. Pat. No. 3,071,244 to Doran discloses the desirability of having portions of tobacco packages accessible for the application of tax stamps while the packages are maintained in a group package.
U.S. Pat. No. 3,027,300 to Farmer relates to the shrink wrapping of bananas, which are wrapped between an upper and a lower polymetric web. The webs are heat sealed and the film is shrunk about the articles. Pin hole perforations are provided in one of the webs prior to the heating operation, permitting the escape of air from the package as the film shrinks thereabout.
U.S. Pat. No. 3,273,302 to Walter illustrates a carton which is wrapped within a single sheet of polymetric film and heated to provide the heat shrink package. A tool is applied to form a tear tab in the already heat shrunk package to facilitate opening thereof after the package has been passed through a a heat shrink oven.
U.S. Pat. No. 3,326,369 to Tolaas, et al. discloses a cardboard carton provided with a pattern of perforations for the specific purpose of providing individual access to the plurality of individual boxes in the package to facilitate price marking on each box.
U.S. Pat. No. 3,344,975 to Stoker, Jr. discloses a shrink wrap package with a tear tab in the shrink wrap material to serve as a started for tearing the shrink wrap material to open the package.
U.S. Pat. No. 3,357,153 to Shaffer discloses a heat shrink oven wherein the heated air may be recirculated for efficient operation.
U.S. Pat. No. 3,442,436 to Kirby, Jr. provides a shrink wrap package with a pair of tab means in the shrink wrap material, enabling the tabs to be pulled to open the package.
U.S. Pat. No. 3,488,912 to Christian relates to the use of a stream of gas to cool a heat seal, whereby the heat seals on the adjacent packages are prevented from contacting each other until the heat seals have cooled below a setting temperature.
U.S. Pat. No. 3,545,165 to Greenwall teaches the method of severing a package into package components along perforations by heat shrinking.
U.S. Pat. No. 3,542,193 to Hewlett provides a heat shrinkable material in combination with a shallow tray for covering one end of articles contained in the heat shrink package.
U.S. Pat. No. 3,640,049 to Fritz, et al. incorporates a heat shrink machine incorporating the cooling of a conveyor belt.
U.S. Pat. Nos. 3,654,829 and 3,804,235 to Anderson provide a punching mechanism for punching a heat shrinkable material prior to heating, to enable the application of tax stamps to tobacco packages.
U.S. Pat. No. 3,834,525 to Morgese teaches a shrink wrap package incorporating two spaced parallel slits in registry with the edges of the containers within the package.
U.S. Pat. No. 3,895,713 to Bunnell discloses a container package having a tray in combination with a plastic covering having apertures therein for enabling the containers to be individually removed from the package.
The aforementioned prior art have solved many of the needs of the prior art shrink wrap packages, but each has many distinct disadvantages. The prior art utilizing perforations require that the perforation of the plastic material be accomplished subsequent to the heat shrinkable material passing through the heat shrink oven. The prior art utilizing cut-outs in the material requires careful registry between the cut-outs and the containers to be packaged. It would be more desirable and more efficient to perforate the sheet prior to passing through the heat shrink oven since this would eliminate the critical registry of perforations required by the prior art. Unfortunately, this method and apparatus has not been heretofore accomplished in the prior art. It is well known, for example, in U.S. Pat. No. 3,545,165, that a perforation in a heat shrinkable material prior to heat shrinking will cause a severing of the heat shrinkable material along the perforation line as the heat shrinkable material is passed through the heat shrink oven.
Therefore, it is an object of this invention to provide an apparatus and method which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advance of the heat shrink packaging art.
Another object of this invention is to provide an apparatus and method for producing a heat shrinkable package having a frangible access panel defined by perforations wherein the perforations are applied prior to the heat shrinking of the heat shrinkable material.
Another object of this invention is to provide an apparatus and method for providing a heat shrinkable package having a frangible access panel defined by perforations which may be accomplished by existing shrink wrap packaging machines with a minimal installation of additional equipment.
Another object of this invention is to provide an apparatus and method for producing a heat shrinkable package having a frangible access panel defined by perforations which does not require a critical registration between the heat shrinkable material and the articles to be shrink wrapped.
Another object of this invention is to provide an apparatus and method for providing a heat shrinkable package having a frangible access panel defined by perforations which is applicable to all type of plastic heat shrinkable material.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the invention. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.